Starter problem resolved!
Battery was only two years old, but very low on water. Filled with distilled water and took to Batteries Plus where it was purchased. Delivered about 500 cranking amps but dropped to under 6 VDC in doing so - evidently not enough to turn motor over.
Left at Batteries Plus overnight for free charge, everything is back to working order.
Remember - check the water on your "maintenance free" battery!
THANKS to all for taking the time to respond to my simple query.